1. Field of the Invention:
The present invention relates to novel compositions comprising aqueous solutions of a cationic organic compound and a xanthan gum. This invention also relates to aqueous plant protection compositions comprised of a cationic pestically active agent.
2. Description of the Prior Art:
Xanthan gum, because of its thickening properties, its great capacity for suspension and its particular rheology, is widely used in a variety of different industries, in particular in the food, construction, textile, paint, paper, cosmetic, agriculture, petroleum, etc., industries.
Xanthan gum is an anionic heteropolysaccharide consisting of D-glucose, D-mannose and D-glucuronic acid units, together with acetyl and pyruvate radicals depending from the mannose units. The proportion of pyruvic acid moieties varies as a function of the specific starting material, the composition of the culture medium, the conditions of fermentation and extraction, and ranges from 2.5 to 4.9% in the industrial grades.
By virtue of its anionic character, xanthan gum is generally considered to be incompatible with cations, an obstacle to the effective use thereof. Thus, it is known in the field of agriculture to use xanthan gums as thickening agents in aqueous compositions containing a water soluble active pesticide, or as a stabilizing and suspending agent in flowable aqueous dispersions containing a finely divided material ("flowables"). These solutions or dispersions are available commercially in the form of a concentrate with 20 to 50% active agent and approximately 0.2 to 2% of xanthan gum. However, this use has to date been limited to nonionic or anionic active agents.
The end user, who in certain cases, in order to avoid several manipulations, seeks to mix the dilute dispersion of a pesticide insoluble in water with a water soluble pesticide such as a quaternary ammonium salt, is confronted with a particularly serious problem. It has been found that, with low concentrations of xanthan in dilute formulations, a complex is formed with quaternary ammonium compounds, manifesting itself in the form of dense insoluble fibers in water. In addition to a reduction in pesticidal activity caused by the formation of such complexes, considerable difficulties are encountered during field spraying, due to a clogging of the spray nozzles by the insoluble fibers.